Launching a week of demonstrations before the G8 summit, the Make Poverty History march piles pressure on US President George W Bush and other leaders to agree to a package of aid, debt relief and trade reform to help lift African nations out of poverty.
A river of protesters clad in white streamed through the cobbled streets of the Old Town, over the Royal Mile and through the commercial district, encircling Edinburgh Castle with a giant human bracelet in white, the symbol of the anti-poverty campaign.
Organisers and Lothian and Borders police estimated that 225,000 people took part in the march.
"We are citizens of the global village. We need help," said Siphiwe Hlophe, 45, who traveled from the African nation of Swaziland to take part in the march.
"The G-8 leaders must live up to their promises. They must be accountable."
Waving banners, blowing whistles and clutching balloons, the marchers called for a massive increase in aid, an end to trade tariffs that hobble impoverished countries and for Africa's debts to be wiped out.
Their peaceful but powerful message was echoed by rock stars and celebrities as a series of Live 8 concerts took place around the world.
an end to trade tariffs
British Prime Minister Tony Blair says the poverty in Africa is a "scar on the conscience on the world" and is pushing for concerted international action when leaders from the United States, Russia, France, Germany, Canada, Russia and Japan join him for a three-day summit starting July 6 in nearby Gleneagles.
"Make Poverty History" and "Trade Justice" demanded banners near the front of the march, next to another with the more specific demand: "Water and Toilets For All".
Cardinal Cormac Murphy-O'Connor, the leader of the Roman Catholic Church in Britain, said the march was intended to send a clear message to the summit, hosted by Prime Minister Tony Blair.
"The leaders of the G8 will see this on television, and see that these are ordinary, good people that want change, that want them to act," he told reporters as the march prepared to set off.
Debt relief, more aid and trade
justice for Africa were core issues
Also at the front were eight suit-clad demonstrators wearing oversized papier mache masks depicting the faces of the G8 leaders who will gather in Gleneagles.
Before the demonstrators set off, Richard Bennett, chairman of Make Poverty History, said he was not worried that the day-long Edinburgh rally would be overshadowed by the Live 8 shows.
"The Live 8 concerts are going to reach billions of people," he told AFP.
Live 8 concerts echoed the Make
Poverty History message
"That means the basic messages are going to reach even further than we could have dared hoped."
He added: "We do believe that our event here is the spearhead around the corner from Gleneagles, and it is absolutely crucial that we get the depth of our messages, the importance of our messages, across here."
Make Poverty History has three core demands: debt relief for Africa's poorest countries, significantly more and better aid from the West and "trade justice" to enable Africa to sell more exports to rich countries.
"They've got to realise their responsibility for all people in a globalised society," said Nichi Hodson, 21, a student in York, northern England, heading to Edinburgh for the march. "If we're going to reap the rewards of globalisation, we have to take the responsibility as well."
The atmosphere in Edinburgh was festive, with a percussion band from Ghana playing and some demonstrators wearing masks depicting the faces of G-8 leaders including Bush, Blair and Russian President Vladimir Putin.
Anxious to avoid a repeat of violence that marred protests against the 2001 G-8 summit in Genoa, Italy, where an officer shot and killed a protester, police mounted a huge security operation.
Scores of shop windows were boarded up along the march route, and officials had cleared away any debris that could be used as missiles. The Scottish Parliament and Holyrood House, Queen Elizabeth II's official residence in Edinburgh, were ringed with steel barricades.
"If we're going to reap the rewards of globalisation, we have to take the responsibility as well"
Police helicopters hovered overhead and officers in riot gear, some on horseback, were on standby.
About 150 anarchists and anti-globalisation protesters dressed in black, many wearing hoods or covering their faces with bandanas, stood out against the sea of white encircling the city.
Some pushed over a barricade and charged at a line of police, before running off down side streets.
Police described the incident as a minor disturbance and said only one marcher had been arrested during the day for a drugs related offence.